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    <title>ShellCheck: SC2170 – Invalid number for `-eq`. Use `=` to compare as string (or use `$var` to expand as a variable).</title>
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    <h1>SC2170 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2170">See this page on GitHub</a>
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    <h2
id="invalid-number-for--eq-use--to-compare-as-string-or-use-var-to-expand-as-a-variable">Invalid
number for <code>-eq</code>. Use <code>=</code> to compare as string (or
use <code>$var</code> to expand as a variable).</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2170.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">read</span> <span class="at">-r</span> <span class="va">n</span></span>
<span id="cb1-2"><a href="SC2170.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> n <span class="ot">-lt</span> 0 <span class="bu">]</span></span>
<span id="cb1-3"><a href="SC2170.html#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb1-4"><a href="SC2170.html#cb1-4" aria-hidden="true" tabindex="-1"></a>   <span class="bu">echo</span> <span class="st">&quot;bad input&quot;</span></span>
<span id="cb1-5"><a href="SC2170.html#cb1-5" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span>
<span id="cb1-6"><a href="SC2170.html#cb1-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb1-7"><a href="SC2170.html#cb1-7" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> <span class="st">&quot;</span><span class="va">$USER</span><span class="st">&quot;</span> <span class="ot">-eq</span> root <span class="bu">]</span></span>
<span id="cb1-8"><a href="SC2170.html#cb1-8" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb1-9"><a href="SC2170.html#cb1-9" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;You are root&quot;</span></span>
<span id="cb1-10"><a href="SC2170.html#cb1-10" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2170.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">read</span> <span class="at">-r</span> <span class="va">n</span></span>
<span id="cb2-2"><a href="SC2170.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> <span class="st">&quot;</span><span class="va">$n</span><span class="st">&quot;</span> <span class="ot">-lt</span> 0 <span class="bu">]</span>        <span class="co"># Numerical comparison</span></span>
<span id="cb2-3"><a href="SC2170.html#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb2-4"><a href="SC2170.html#cb2-4" aria-hidden="true" tabindex="-1"></a>   <span class="bu">echo</span> <span class="st">&quot;bad input&quot;</span></span>
<span id="cb2-5"><a href="SC2170.html#cb2-5" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span>
<span id="cb2-6"><a href="SC2170.html#cb2-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-7"><a href="SC2170.html#cb2-7" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> <span class="st">&quot;</span><span class="va">$USER</span><span class="st">&quot;</span> <span class="ot">=</span> root <span class="bu">]</span>    <span class="co"># String comparison</span></span>
<span id="cb2-8"><a href="SC2170.html#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb2-9"><a href="SC2170.html#cb2-9" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;You are root&quot;</span></span>
<span id="cb2-10"><a href="SC2170.html#cb2-10" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>You are comparing a string value with a numerical operator, such as
<code>-eq</code>, <code>-ne</code>, <code>-lt</code> or
<code>-gt</code>. These only work for numbers.</p>
<p>If you want to compare the value as a string, switch to the
equivalent string operator: <code>=</code>, <code>!=</code>
<code>\&lt;</code> or <code>\&gt;</code>.</p>
<p>If you want to compare it as a number, such as
<code>n=42; while [ n -gt 1024/8 ]; ..</code>, then keep the operator
and expand the operands yourself with <code>$var</code> or
<code>$((expr))</code>: <code>while [ "$n" -gt $((1024/8)) ]</code></p>
<h3 id="exceptions">Exceptions:</h3>
<p>None.</p>
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